Cleaning formulation

ABSTRACT

An alkaline, aqueous composition suitable for cleaning carpets and other surfaces, which composition comprises a) 0.1 to 50% w/w of a first cleaning agent; b) 0.1 to 20% w/w of a second cleaning agent; c) 0.1 to 10% w/w of a third cleaning agent; and d) 0.1 to 10% w/w of a surfactant and optionally minor amounts of additives, with the balance being made up of water. This formulation is preferably used in conjunction with a neutralizing solution. A method for cleaning carpets and other surfaces is also disclosed.

The present invention relates to an improved cleaning system. It isparticularly applicable to cleaning carpets and upholstery. Theinvention includes a new method for cleaning; new cleaning apparatus;and new compositions for use in the method and apparatus.

It is important to keep carpets clean. Carpets help purify theenvironment by accumulating particulates and gases from the feet andfootwear of the people who walk over them as well as from thesurrounding atmosphere. Soiled carpets, however, are not aestheticallyappealing and wear poorly. Left uncleaned, they will eventually releaseparticulates and gases back into the air. In closed-circulationbuildings, heavily-soiled carpets will cease to help clean theenvironment, and may become a source of air pollution that couldcontribute to health problems.

Carpet-cleaning and maintenance programmes have a direct impact oncarpet appearance and performance. Proper cleaning and maintenance cantherefore keep carpets looking new and beautiful, extend their lifespanand contribute to a healthier indoor environment. Additionally, moderncarpets which have been pre-treated with soil- and stain-retardantsrequire special treatment to clean them properly whilst maintainingtheir soil- and stain-resistance.

There are a number of known carpet-cleaning and maintenance routines:loose and fitted carpets may be cleaned in situ using powder-formproducts which are scattered onto the carpets and removed again undersuction after a mechanical treatment.

So-called ‘steam cleaning’ is another method offered by many cleaningcontractors, but this method tends to saturate the carpet, including thecarpet backing, as steam condenses once in contact with the carpet. Thisand other aqueous treatments tend to leave the fabric being cleanedthoroughly wet. In the case of carpets or upholstery, this is a majordisadvantage. For example, a wet carpet should not be walked on until itis dry, which also means that any furniture cannot be put back intoposition for many hours.

In addition, if the carpet backing gets wet, it can shrink and thisshrinkage can be of an extent to pull a fitted carpet away from thewall, particularly in a large room.

Similar problems exist with other substrates to be cleaned, such asfabrics, which can shrink once they are thoroughly wet.

A widely-used, conventional method involves the application of adetergent solution to the carpet, followed by extraction of detergentplus soils. Detergents, however, only attack water-soluble dirt.Therefore, when water-insoluble materials, such as grease, are presentin the carpet, organic solvents must separately be applied andextracted.

Although detergents and other cleaning agents have conventionally beenemployed as carpet cleaning agents, as currently applied they can bedetrimental to carpet appearance. Conventional detergents and cleaningagents used in carpet cleaning are highly alkaline; their pH isgenerally at least about 10-12. Residues from these alkaline productstend to remain on the carpet after the cleaning process is complete.This is undesirable, because alkaline conditions can affect the colourand stability of some dyes used in carpet and upholstery fabrics. Inaddition, these alkaline deposits can cause the carpet to become dirtierquicker than would otherwise have been the case.

Such conventional cleaning agents may also contain optical brightenersand soil retardants. The repeated use of these cleaning agents cantherefore also lead to build-up of soil retardant and optical brightenerin the carpet or on its surface, which, together with alkaline deposits,also promote rapid resoiling and degradation of carpet fibre,particularly in the case of nylon, and also can cause carpet colour tofade due to enhanced UV sensitivity.

Accordingly, it is an object of the present invention to overcome orminimise some or all of the problems outlined above.

According to a first aspect of the present invention, there is thereforeprovided an alkaline, aqueous composition suitable for cleaning carpets,which composition comprises:

-   -   (i) 0.1 to 50% w/w of a first cleaning agent;    -   (ii) 0.1 to 20% w/w of a second cleaning agent;    -   (iii) 0.1 to 10% w/w of a third cleaning agent; and    -   (iv) 0.1 to 10% w/w of a surfactant.

All weights expressed herein are based on the total weight of the totalcomposition, unless stated otherwise.

The composition of the invention is preferably in the form of afinely-balanced solution but may also be a weak emulsion. As well as oncarpets, textiles, furnishings and the like, the solution may also beused on other surfaces, such as metal, glass and the like.

The first cleaning agent is water-soluble and is preferably one that isa complexing agent for complexing metal ions, and may also act as analkaline detergent builder and/or water softener. More preferably, it isa non-acidic cleaning agent.

The second cleaning agent is also water-soluble or miscible and ispreferably a binding agent for binding together the other ingredients inthe composition and/or for maintaining the other components of theformulation in aqueous solution, emulsion or dispersion and/or otherwisefor coupling together the other components of the composition. Morepreferably, it is miscible with water to form an aqueous solution.

The third cleaning agent is preferably an organic solvent capable ofacting as a solubiliser or dissolving agent for grease, fats and thelike that, more preferably, is a liquid that is dispersible in the othercomponents of the composition and/or is stable in aqueous conditions.

Therefore, the present invention preferably provides a water-basedcleaning composition comprising:—

-   -   (a) 0.1 to 50% by weight of detergent builder and water        softener;    -   (b) 0.1 to 20% by weight of coupling agent:    -   (c) 0.1 to 10% by weight of organic solvent:    -   (d) 0.1 to 10% surfactant; and, optionally,    -   (e) minor amounts of additives the balance being water.

This formulation provides significantly improved grease andstain-removing properties, compared to known formulations. The mainingredients of the formulation having cleaning properties are components(a), (b). (c) and (d), as defined above.

Preferably, the cleaning composition further comprises one or more ofthe following additional components (additives), including:—

-   a colouring agent, such as a dye;-   a perfume;-   a biocide, preservative or ant-septic; and/or-   an anti-static agent.

In the compositions of this invention, the conditions for two or morecomponents may be satisfied by one ingredient.

Preferably, in the compositions of this invention, halogenatedsurfactants and solvents are not used. Halogenated surfactants tend tobe expensive and halogenated solvents are not environmentally friendly.The present invention therefore further provides an alternative carpetcleaning formulation that avoids the use of these undesirableingredients. Similarly, many prior art cleaning compositions incorporateammonia, or ammonium or other nitrogen-based ingredients; these can alsobe avoided by using the composition of the present invention.Accordingly, the present invention further provides a cleaningcomposition that excludes one or more of: halogenated ingredients andnitrogen-based ingredients.

Preferably, the complexing agent, component (a), comprises one or moresolid, water-soluble, inorganic or organic compounds having a pH greaterthan 7 and preferably such that the pH of the total composition isgreater than 8, more preferably in the range of from 8 to 12, especiallyabout 10. Such suitable alkaline compounds may be selected from:—

-   aminopolycarboxylic acids;-   nitrilotriacetic acid;-   alkylene diamine derivatives of carboxylic acids, such as ethylene    diamine diacetic acid and ethylene diamine tetra-acetic acid (EDTA);    and-   phosphonates, such as pyrophosphoric acid and polyphosphoric acid;-   and salts thereof, such as alkali or alkaline earth metal salts.

These lists are not intended to be limiting in any way and any member ofthis general class of reagent can be employed. However, preferredcompositions of this invention are those that do not include silicates,which (in use) could leave deposits or scale on the surface to becleaned. The concentration of component (a) is generally in the range of0.1-50% by weight, with a preferred range of 1-10% w/w. A particularlypreferred range is from 2 to 8% w/w.

In a particularly preferred embodiment, the complexing agent, component(a), comprises an inorganic complexing agent comprising one or more ofpyrophosphoric acid and polyphosphoric acid; and salts thereof.

Preferably, the binding or coupling agent, component (b), comprises aliquid, water-soluble or miscibie, oxygenated organic solvent, such asone or more compounds selected from ethers, alcohols and esters, inparticular, an ether of an alkylene glycol.

Suitable compounds for use as component (b) include:—

-   an ether of ethylene glycol;-   an ether of propylene glycol, such as dipropylene glycol monomethyl    ether and/or propylene glycol N-butyl ether; and-   an aliphatic alcohol, such as a C₁-C₆, preferably C₂-C₄, alkanol,    such as isopropyl alcohol and/or ethanol.

Especially preferred is when component (b) comprises as dipropyleneglycol monomethyl ether and/or propylene glycol N-butyl ether,particularly a mixture thereof, more particularly in a ratio of fromabout 2-3:1, especially 70:30, respectively.

Typical concentrations for the binding/coupling agent range from0.1%-20% by weight with a preferred range being between 1%-10% w/w and aparticularly preferred concentration being 3 to 5% by weight.

Preferably, the organic solvent, component (c), is any organic liquidthat has particular cleaning effect on grease and fats. It is thereforemore preferably immiscible with water in the absence of a surfactant andmay comprise a medium-chain hydrocarbon and/or a fatty add ester. Forexample, the organic solvent may comprise one or more compounds selectedfrom:—

-   C₉ to C₁₅ linear aliphatic hydrocarbons, such as C₉ to C₁₅ low    aromatic content kerosene;-   C₆ to C₁₅ cyclo-aliphatic hydrocarbons;-   fatty acid alkyl esters, such as C₁₆ to C₂₂ fatty acid alkyl esters,    preferably, C₁₆-C₁₈ fatty acid (C₁-C₄)alkyl esters.

The above list of organic solvents is not intended to be limiting in anyway. In principle, it is possible to use any non-toxic, organic solventfor this purpose where the solvent has the ability to dissolve greaseand fats. Especially preferred is when component (c) comprises anon-flammable (under the conditions of use), odourless, water-stablemedium chain organic compound, such as a fatty acid derivative, analkanol eg isopropanol; a glycol or a dibasic ester. Most preferred is afatty acid methyl ester.

The organic solvent is generally present in a concentration of 0.1-10%by weight with a preferred concentration range being 1% to 5% by weightand a particularly preferred concentration being from 1 to 3% w/w, suchas about 2% w/w. More preferably, the amount of solvent is kept to theparticularly preferred range for admixture with the lower ranges ofsurfactant. Higher amounts of the organic solvent will require higheramounts of surfactant, which would lead to the formation of an emulsion,rather than a solution. Such emulsions also form part of this inventionbut are not preferred over the solutions, in particular because theamount of surfactant required would tend to result in foam.

Preferably, the surfactant, component (d), comprises a liquid,water-soluble or miscible, low-foaming, non-ionic, anionic or amphotericsurfactant, particularly an emulsifying agent that enables the organicsolvent, component (c), to mix with the other components of thecomposition, such as ethers of fatty alcohols eg an ethoxylated alcohol.However, there is a very wide range of known surfactants and. Inprinciple, any of these can be employed, as suitable, given theparticular formulation. In particular, the surfactant preferably has theability to bring any soils from the surface to be cleaned into solutionor admixture with the composition of the invention.

The surfactant is generally present in a concentration of 0.1-10% w/wwith a preferred range being 16% w/w and a particularly preferredconcentration being in the range of from 3 to 4% w/w, such as about 3.5%by weight. In any case, the amount of surfactant required is, atminimum, that sufficient to maintain component (c), such as a fatty acidmethyl ester, in liquid dispersion in the composition.

It is also desirable to add a biocide, which may be selected from anyknown biocides suitable for the purpose. Typical examples are quaternaryammonium salts, such as benzalkonium chloride. The biocide may bepresent in an amount in the range of from 0 to 5% w/w, such as about 1to 2% w/w. Benzalkonium chloride is also a suitable anti-static agentfor use in the composition.

Furthermore, benzalkonium chloride, when present, may comprise theprimary contributor to the pH of the solution. Accordingly, the amountof benzalkonium chloride present may be such as to result in a solutionhaving a pH greater than 7 and preferably such that the pH of the totalcomposition is greater than 8, more preferably in the range of from 8 to12, especially about 10.

It is also preferable to add a dye and/or a perfume to improve theappearance and odour of the cleaning formulation. Such dyes and perfumesfor the use in cleaners are well known to those skilled in the art andmay be present in an amount in the range of from 0 to 3% w/w, such asabout 0.1-0.2% w/w perfume and/or less than about 0.1% w/w, eg less thanabout 0.01% w/w, colouring agent.

In the formulations of the invention, unlike in some prior artformulations, viscosity control is not essential, although the viscosityof the solution tends to be low and of a similar order to that of wateror slightly higher. The composition is made up to 100% with water. Theamount of water therefore is preferably in the range of from about 60 to90% w/w, such as in the range of from about 70 to about 80% w/w.

The composition may be presented in ready-to-use form or in the form ofa liquid concentrate for dilution with an appropriate amount of water.Conveniently, the composition may be in the form of a liquid concentratefor dilution with, in the range of from, 1 part concentrate to 8 partswater, preferably in the range of from 2 to 6 parts, such as 4 partswater. The weight percentage ranges, at their broadest, expressed aboveare suitable for both concentrate and final, diluted solution. However,preferred, narrow ranges are generally expressed in terms of aconcentrate, for dilution 1 part concentrate with 4 parts water. The pHof the concentrate is in the same range as that mentioned above withrespect to the final solution.

Accordingly, the present invention further provides a liquid concentratefor dilution with water to provide an alkaline, aqueous compositionsuitable for cleaning carpets, which composition is as definedhereinabove.

There is also provided a method for the preparation of a solution orconcentrate according to this invention, which method comprises mixingtogether components (a) to (c), together with the water and any suitableoptional ingredients such as biocide, and thereafter adding to thatmixture component (d) and any suitable optional ingredients such asorange terpenes.

In order to assist in the objective of reducing or ameliorating build-upof alkali on or in the carpet, an alkaline cleaning composition ispreferably used in association with a neutralising composition, wherebythe pH of the combined compositions (in use) is reduced to aboutneutral, as indicated eg using a standard litmus paper test. By ‘aboutneutral’ in this context is meant that the pH is in the range of from5.5 to 8.5, but more preferably in the range of from 6.5 to 8, such asabout 7.5 or slightly alkaline.

Therefore, according to a second aspect of the invention, there isprovided a two part cleaning composition comprising:

-   -   (a) an alkaline cleaning composition, such as preferably a        cleaning composition as defined hereinabove: and    -   (b) a neutralising composition comprising an aqueous solution of        a non-oxidising acid.

A wide variety of acids can be used in the neutralising composition, butpreferably the non-oxidising acid comprises one or more compoundsselected from mild or weak inorganic and organic acids. Preferred suchadds are non-toxic, food or pharmaceutical-grade acids, for health andsafety reasons. It is particularly preferred to use a nonoxidising,organic add whose alkali metal or alkaline earth metal salts arewater-soluble. Suitable organic acids are therefore citric acid; aceticacid; succinic acid; tartaric acid; tannic acid; propionic acid; andglycolic acid. It is also possible to use certain inorganic acids, suchas sulphamic acid. The pH of the neutralising solution is preferably inthe range of from 1.5 to 3.5, such as about 2.

The acid is typically supplied as an aqueous solution of, say, one partby weight of acid in forty parts by weight of water. One part of thisstock solution may then be further diluted with, in the range of from,20 to 80 parts by water before use. That is to say, one liter of stockacid solution is diluted to give a final volume of from 20 to 80 liters.Preferably, the dilution ratio is in the range of from 1:40 to 70, morepreferably about 1:60. Once diluted, the pH of the neutralisingcomposition is preferably in the range of from 2.5 to 4.5, morepreferably in the range of from about pH 3 to 4. For example, the pH ofa neutralising composition diluted 1:40 is preferably about 3.

It is known to apply an aqueous dispersion of an alkaline cleaning agentto a carpet and mechanically to buff the carpet to cause dirt totransfer from the carpet to the buffing pad. It has now surprisinglybeen discovered that it is highly advantageous to soak the buffing padsin hot, neutralising composition immediately prior to buffing.

This improvement provides a number of advantages. First, as mentionedabove, the acid in the neutralising composition tends to neutralise thealkaline cleaning composition on the carpet so that the carpet is leftat a substantially neutral pH of 5.5-8.5 on completion of the cleaningprocess. This protects the dyes in the carpet from discolouration, andtends to reduce the rate of re-soiling and the degradation of carpetfibres.

Secondly, the temperature of the buffing pad is maintained, for the timeit takes to apply neutralising solution to the carpet, well aboveambient. The raised temperature of the buffing pad appears significantlyto increase the rate and extent to which dirt is extracted from thecarpet, believed to be as a result of enhanced capillary action causingthe dirt to wick up the fibres.

Therefore, according to a third aspect of the invention, there isfurther provided a method suitable for cleaning carpet, upholstery orthe like (referred to herein, collectively, as ‘carpet’), which methodcomprises:—

-   -   (a) applying to the carpet an alkaline cleaning composition,        such as preferably a cleaning composition as defined        hereinabove, in an amount sufficient to wet the carpet fibres;        and    -   (b) mechanically buffing the carpet with a pad soaked in a        neutralising composition comprising an aqueous solution of a        non-oxidising acid in an amount sufficient to substantially        neutralise the alkaline cleaning composition remaining on the        carpet.

Preferably, the aqueous acidic solution is heated to a temperature inthe range of from 50° to 95° C., more preferably in the range of from 70to 85° C. prior to buffing the carpet, whereby the pad, after immersionin the neutralising composition, is in that temperature range when thebuffing starts.

Preferably, the alkaline cleaning composition comprises a water-basedcleaning composition as described herein. Preferably, the neutralisingsolution comprises an aqueous acidic solution as described herein.Accordingly, the method of the invention is most preferably carried outusing the two-part cleaning composition of this invention. Morepreferably, the method is carried out in a manner whereby the ratio ofneutralising solution to cleaning composition is greater than one, suchas in the range of from 2 to 4:1, eg about 10:3, respectively.

Conveniently, doses of about 15 to 25 ml, such as about 18 to 22 ml, ofthe neutralising composition are applied, per pad, to the carpet. As aguide, about 10 liters of neutralising composition are required per 100square meters of carpet.

Preferred pads for use in the method according to this invention aresubstantially flat, circular pads, comprising generally synthetic fibressandwiching an absorbent layer. For example, they may comprise apolyester/rayon mixture that is capable of being in contact over itswhole application face with the carpet, when in use.

Because the buffing pads have to be changed frequently, a specialheating device has been developed to keep the pads both hot andsaturated with acid solution. In its simplest form, this heating devicecomprises a liquid-tight tank, having a removable lid through which thepads can be inserted and withdrawn. The tank is conveniently heated byway of a thermostatically controlled heating element or the like, sothat the temperature may be controlled between set temperature limits,as suggested above. The tank is constructed from any suitable materialthat is inert to the acid used. Typically, plastics materials orstainless steel can be used.

There are several desirable features that may optionally be incorporatedinto the tank. Because the pads are normally circular in shape, it ispreferable that the lid to the tank and the access port are alsocircular. This facilitates inserting and removing the pads.

Because the pads may conveniently be kept immersed in the hot acidicsolution whilst awaiting use and yet need to be accessible, preferablywithout having to delve too deeply into the acidic solution as each padin turn is required, a spring-loaded dispenser, of the type used tostore and dispense plates in a canteen, can be incorporated into thetank. This ensures that, however many pads are waiting in the tank, thetop pad is always within easy reach. Alternatively, pads may be immersedin the neutralising composition, one-by-one, as required.

The tank is preferably adapted to be mounted on wheels, so that it canfollow the buffing machine around the area to be cleaned. However, forconvenience of storage, the wheels may be provided on a detachabletrolley or wheel-base, separate from the body of the tank.

The following examples are provided for illustration of the inventiononly and are not intended to be limiting thereof.

EXAMPLE 1 Ready-to-Use Cleaning Composition

A water-based cleaning composition was prepared by mixing the followingingredients:—

% of total composition Tetrapotassium pyrophosphate 2.00 Propyleneglycol ether (DOWANOL DPM) 2.95 (C9 to C15) Aliphatic hydrocarbon(kerosene) 1.91 (EXXOL D80) Ethoxylated alcohol 3.308 Benzalkoniumchloride (50% solution) 0.092 Dye/Perfume Q/S Water Q/S to 100%

EXAMPLE 2 Cleaning Composition Concentrate

An alkaline, aqueous composition suitable for dilution, prior to use, 1part to 4 parts water, was prepared by mixing the followingingredients:—

% of total concentrate Tetrapotassium pyrophosphate 8.00 Dipropyleneglycol monomethyl ether 3.50 Propylene glycol N-butyl ether 1.50(DOWANOL PMB) (C16-C18) Fatty acid methyl ester 1.50 Ethoxylated alcohol(SYNPERONIC 916) 3.29 Benzalkonium chloride (50% solution) 1.536 Dye0.0008 Terpenes 0.15 Water 80.3492

1. An alkaline, aqueous cleaning composition which comprises: (a) 0.1 to50% by weight of detergent builder selected from the group comprisingpyrophosphoric acid and polyphosphoric acid and salts thereof; (b) 0.1to 20% by weight of a coupling agent consisting essentially of anoxygenated organic solvent; (c) 0.1 to 10% by weight of a fatty acidalkyl ester and/or dibasic ester; (d) 0.1 to 10% surfactant; and,optionally, (e) a minor amount of one or more additives.
 2. Acomposition according to claim 1, further comprising one or more of thefollowing additives: a colouring agent; a perfume; a biocide; apreservative; an anti-septic; and/or an anti-static agent.
 3. Acomposition according to claim 1 further comprising benzalkoniumchloride.
 4. A composition according to claim 1, wherein component (b)consists essentially of a liquid, water-soluble oxygenated organicsolvent.
 5. A composition according to claim 1, wherein component (b)consists essentially of an ether of an alkylene glycol.
 6. A compositionaccording to claim 1, wherein component (b) consists essentially of apropylene glycol ether.
 7. A composition according to claim 1, whereincomponent (c) consists essentially of a C₁₆ to C₂₂ fatty acid alkylester.
 8. A composition according to claim 1, wherein component (c)consists essentially of a C₁₆-C₁₈ fatty acid (C₁-C₄) alkyl ester.
 9. Acomposition according to claim 1, wherein component (d) consistsessentially of a low-foaming surfactant capable of keeping component (c)in solution in the composition.
 10. A composition according to claim 1,wherein component (d) consists essentially of an ether of a fattyalcohol.
 11. A composition according to claim 1, wherein component (d)consists essentially of an ethoxylated alcohol.
 12. A compositionaccording to claim 1 in the form of a solution.
 13. A compositionaccording to claim 1, which is substantially free from halogenatedsurfactants and solvents; and/or ammonia; ammonium and othernitrogen-based ingredients; and/or silicates and other depositinginorganics.
 14. A composition according to claim 1 having a pH in therange of from 8 to
 12. 15. A composition according to claim 1 having apH of
 10. 16. A composition according to claim 1 comprising in the rangeof from 60 to 90% w/w water.
 17. A concentrate composition suitable fordilution with, in the range of from, 1 to 8 parts water to prepare acomposition according to claim
 1. 18. A method for cleaning a surfacewhich method comprises applying to the surface an alkaline cleaningcomposition as defined in claim 1, in an amount sufficient to wet thesurface.
 19. The use of a composition according to claim 1 in thepreparation of an aqueous solution for cleaning a surface, such ascarpet, upholstery, textiles, furnishings, metal and glass.
 20. A methodof preparing a composition according to claim 1, which method comprisesbringing the components into intimate physical admixture to form anaqueous solution or weak emulsion.
 21. An aqueous alkaline cleaningcomposition consisting essentially of: (a) pyrophosphoric acid orpolyphosphoric acid, or a salt thereof; (b) an ether of an alkyleneglycol; (c) a C₁₆-C₂₂ fatty acid alkyl ester; (d) an ether of a fattyalcohol; and optionally, (e) a colouring agent; perfume; biocide;preservative; anti-septic; and/or anti-static agent.
 22. A two-partcleaning composition suitable for cleaning carpets, which compositioncomprises: (a) an aqueous alkaline cleaning composition comprising (i)0.1 to 50% by weight of detergent builder selected from the groupcomprising pyrophosphoric acid and salts thereof; (ii) 0.1 to 20% byweight of coupling agent; (iii) 0.1 to 10% by weight of fatty acid alkylesters and/or dibasic esters; (iv) 0.1 to 10% surfactant; and,optionally, (v) a minor amount of one or more additives; and (b) aneutralising composition; whereby, in use, the pH of the combinedcompositions (a) and (b) is in the range of from 5.5 to 8.5.
 23. Acomposition according to claim 22, wherein the alkaline cleaningcomposition (a) consists essentially of: (i) pyrophosphoric acid orpolyphosphoric acid, or a salt thereof; (ii) an ether of an alkyleneglycol; (iii) a C₁₆-C₂₂ fatty acid alkyl ester; (iv) an ether of a fattyalcohol; and optionally, (v) a colouring agent; perfume; biocide;preservative; anti-septic; and/or anti-static agent.
 24. A two-partcleaning composition according to claim 23, wherein, in use, the pH ofthe combined compositions (a) and (b) is about 7.5.
 25. A two-partcleaning composition according to claim 23, wherein the neutralisingcomposition comprises an aqueous solution of a non-oxidising acid.
 26. Atwo-part cleaning composition according to claim 23, wherein theneutralising composition (b) is in the form of an aqueous solution ofone part acid to, in the range of from, 40 to 70 parts water.
 27. Atwo-part cleaning composition according to claim 23, wherein theneutralising composition (b) is in the form of an aqueous solution ofone part acid to 60 parts water.
 28. A method suitable for cleaning acarpet surface, which method comprises:— (a) applying to the surface analkaline cleaning composition in an amount sufficient to wet thesurface; and (b) mechanically buffing the surface with a pad soaked in aneutralising composition in an amount sufficient such that the pH of thecombined compositions is in the range of from 5.5 to 8.5.
 29. A methodaccording to claim 28, wherein the neutralising composition is heated toa temperature in the range of from 50° to 95° C., prior to buffing thesurface.
 30. A method according to claim 28, wherein the neutralisingcomposition is heated to a temperature in the range of from 70° to 85°C., prior to buffing the surface.
 31. A method according to claim 28,wherein the alkaline cleaning composition comprises a water-basedcleaning composition as defined in claim
 1. 32. A method according toclaim 28, using the two-part cleaning composition according to claim 22.33. A method according to claim 28, in which the ratio of neutralisingcomposition to cleaning composition is greater than one.
 34. A methodaccording to claim 28, in which the ratio of neutralising composition tocleaning composition is in the range of from 2 to 4:1, respectively. 35.A method according to claim 28, wherein the neutralising composition isheated in a tank prior to application to the surface.
 36. A methodaccording to claim 28, wherein the pad is heated prior to application tothe surface.
 37. A method according to claim 28, wherein the pad isheated by immersion in the neutralising composition prior to applicationto the surface.
 38. A method according to claim 18, in which the surfacebeing cleaned comprises carpet fibers.
 39. A composition according toclaim 6, wherein said propylene glycol ether consists essentially ofpropylene glycol N-butyl ether.